Follow the advice of Thomas Jefferson: Trade with All; Entanglements with None. And then I would enact Ron Paul's best idea: close out 160 military bases overseas, bring the troops home, and save a trillion dollars a year.

What/who changed my life and why

First and foremost, Jesus Christ, because he put my life in perspective. Also, as absurd as it may sound, the Doctor Who TV series because it put the concept of "time" in perspective.